This invention relates generally to adhesive attachment assemblies including adhesive attachments or the like and mounting fixtures and related methods of use for securing an adhesive attachment onto a supporting surface or substrate. More specifically, this invention relates to improvements in such adhesive attachments and mounting fixtures particularly of the types described and claimed in commonly assigned U.S. Pat. Nos. 4,302,492; 4,338,151; and 4,390,576.
In many instances, it is necessary or desirable to install an element such as a patch, threaded screw stud, or the like onto a supporting substrate by means of an adhesive connection or bond. For example, it may be necessary to apply a thin patch to the skin of an aircraft or the hull of a boat or other structure to repair a hole therein. Alternately, it may be desirable to mount a threaded screw stud or other device onto a substrate such as the windshield of an automobile or the like without forming a hole within the substrate. As another alternative, in many modern aerospace applications, it is frequently desirable to attach a threaded stud or patch or other device onto a nonmetallic substrate formed from composite materials or the like without forming a mounting hole or otherwise interrupting the surface of the substrate. As one such example, it is known to attach a threaded stud onto a composite material substrate, wherein the stud supports a conventional cable clamp through which a bundle of electrical conductor wires or the like is threaded. To achieve a maximum strength bond of the adhesive attachment to the substrate, it is desirable to apply a positive force pressing the attachment against the substrate during at least an initial time period for curing of a selected bonding agent at the attachment/substrate interface.
In the past, a variety of fixture devices have been proposed for use in temporarily supporting an adhesive attachment upon the surface of a substrate during the cure time of a bonding agent at the attachment/substrate interface. In general, these fixture devices have required some form of mechanical connection to the substrate by means of screws or other mechanical fasteners such as clamping jaws, etc. However, such devices are not well suited for use with substrates having extended surface areas lacking surface interruptions such as threaded holes or edges for mechanical engagement by the fixture device. Moreover, such fixture devices are not adapted for use with substrates formed from relatively fragile or thin-walled materials incapable of withstanding localized stress attributable to the fixture device.
Other types of fixturing devices have been proposed using suction cups for supporting an attachment upon a substrate during the cure time of a bonding agent. However, such suction cup devices are inherently restricted to use with relatively smooth-finished substrates and further are generally ineffective to exert any significant positive force urging the attachment toward the substrate. Still other fixturing devices have utilized inflatable air bags or bladders held adhesively onto the substrate during bonding agent cure time to press against the adhesive attachment. However, such flexible air bags have inadequate structural integrity to apply uniform positive force to the adhesive attachment, resulting in uneven distribution of the bonding agent at the attachment/substrate interface and/or curing of the bonding agent with less than full bonding strength.
Improved fixturing devices for mounting adhesive attachments are described and claimed in commonly assigned U.S. Pat. Nos. 4,302,492; 4,338,151; and 4,390,576. More particularly, the adhesive attachments described in these patents are carried by mounting fixtures designed for temporary securement to the substrate by means of a pressure sensitive adhesive or the like. The support fixtures include force-bias or spring means activated when the fixtures are mounted on the substrate to apply a positive force urging an attachment into positive bearing engagement with the substrate. In the specific embodiments, the force-bias or spring means includes a movable component adapted to displace the adhesive attachment from a first position carried substantially out of bearing engagement with the substrate to a second position with the attachment pressed positively against the substrate. An over-center type spring plate constitutes the movable component in most of the described embodiments. Further improved mounting fixtures of one-piece molded plastic and including means for maintaining alignment during movement into bearing engagement with the substrate are disclosed in the above-referenced copending application Ser. No. 772,610.
The present invention relates to further improvements in adhesive attachments and mounting fixtures therefor. More specifically, the present invention relates to improved adhesive attachments formed from multiple components for use in specialized substrate environments, for example, for secure bonding onto substrates formed from composite materials. In addition, the present invention relates to further improvements and simplifications in adhesive attachment mounting fixtures and their related methods of use for quickly and easily installing adhesive attachments onto a substrate.